It is frequently desired to mix fluids, particularly liquids such as water, with some chemical in metered quantities. Where the exact ratio of the two fluids to be mixed is not important and the two fluids are available at the same pressure, it is possible to mingle the two pressure streams directly through suitable valves governing the relative proportions. However, if one of the fluids must be metered accurately and is available at a lower pressure than the other, there is no satisfactory existing metering apparatus.
One particular application of this invention is to inject a bloat control chemical into the drinking water fed to cow troughs to control bloat in cows. In dry weather cows drink 12 - 22 gallons of water per day. In wet weather they drink less, but since cows are habit forming creatures, a cow which has bloat in wet weather will from past experience know that drinking water helps relieve the discomfort. It is, of course, under wet weather conditions when the farmer is least likely to inspect his stock for signs of bloat. In a preferred arrangement of this invention, the quantity of bloat control fluid injected into the water supply varies with the rate of flow of water through the device. Thus on a fine day when a large amount of water is consumed, the concentration of bloat control fluid in the water is lower than on a wet day when a lesser amount of water will be consumed. Thus a cow which will naturally drink a lesser amount of water on a wet day will still get the requisite amount of chemical needed to control any bloat condition.
The control of bloat in cows is only one possible application of this invention. It can be applied to mix oil and petrol for 2-stroke fuel, in fertiliser and weed control systems and where gases are required to be mixed, to name just a few.